One very obvious deficiency on the turbine these past few days during which we had fantastic wind was that the mast bent away from the wind and that set up a swaying motion for the blades. I'm quite sure that the turbine is not happy with this situation.

The gyroscopic effect on the blades induced all sorts of forces with the net effect that the whole turbine shook and sometimes even turned out of the wind. I'm also quite sure that because of this imbalance we lost a lot of power that would otherwise have come down the line to the batteries. The stay wires were whipping so I tightened them real tight but the action was taking place in the final 1.7 meter 38mm stainless steel pipe, above the attachment of the staywires.

I really don't like living so close to the edge of disaster - everything was being stressed to the limit. I engaged the electrical brake and started planning.

I bought a 1.7 meter length of 60mm steel pipe from the salvage and then went to the engineering workshop with a sketch of parts I needed machined so that I could put the 38mm pipe through the the "new" 60mm pipe. (I saved the drawing and that is included below). The 60mm pipe will be welded to the existing 60mm pipe. The staywire configuration will remain much the same as it is now.

I'm pretty damn sure that this will solve the mast problem. It will be heavy but it will be strong !!! The 38mm stainless steel pipe still has the 34mm stainless steel pipe inside it. The only bending that can take place will be the portions of the 38mm pipe below the swivel (about 10 cm) and above the swivel (about 20 cm). The rest of the mast should be solid.

I'm thinking of the tail but that's the next problem and I don't want to get my problems mixed up !!!!

I have had a bracket made to cater for larger blades. It uses a 20mm shaft (in place of the 12mm), and a 50mm pipe (in place of the 38mm one). I have also made parts for a swivel mount for the 50mm size.

It would fit your stator and rotor disks - just the bearing rings would need to be replaced (the two smaller steel disks), as well as the bearings (to fit the 20mm shaft).

I'd be happy to covert your system to the larger size, if you are keen, and are in Cape Town again sometime.

What I saw with strong wind was a very unstable turbine. I cured about 50% by making the tail bigger and heavier and more rigid. However, when standing below the turbine I could literally see the stainless steel pipe bending and the turbine swaying and I'm interested to see what happens when that cannot happen.

I'm quite sure that the 20mm shaft will give better stability and last longer but I really want to see how well I can make this turbine run. I'm still quite happy tinkering. Eventually it will all work perfectly and smoothly and I'll move on to the next project.

Which incidentally is already waiting in the wings. My son sent me specs to make a "battery rescuer" that some technical guy in the aero world says works !! My son writes technical articles for aero magazines and so he knows most of the guys doing the same thing. I wouldn't call it a "desulphator" but I couldn't care less, if it rescues my two second-hand Telkom batteries and my two second-hand golf-cart batteries then I'll be happy. We shall see.

I overdo things - that's me. To that end I've got a perspex shower door - one of those that is half a door width wise. This I am fashioning into a tail - it will be painted so no one will ever suspect. I've concocted a piece of square tubing to fit solidly onto the mast and it is extended by an aluminium weedeater shaft that I picked up at the salvage. The door will be cunningly attached by small aluminium tubes to the shaft.

It will have a huge area and it will be light. It will also be smooth on the same side as the offset of the turbine to the mast. The small tubes and fittings will be on the other side. This is not a casual decision as I learnt by my son's experience that faster moving air has a lower pressure than slower moving air so there will be a pressure on the tail to counteract the offset.

As an aside. A long time ago, my son is 40, the passenger door of his Cessna swung open on take-off. He was grounded for a couple of months for that and now it's always a big palaver about door checking before he will release the brake and start his run. In my case he now leans over me and locks it himself. The door swung open and "locked" about half way open due to aerodynamics. The rushing air over the door caused a low pressure on the outside relative to the still but high pressure air of the cabin. The weight of the air against the door tried to close the door so there was a point where the two opposing forces balanced and there the door STUCK ! He knew immediately what was happening and didn't waste time or energy trying to close the door (which would have been impossible), he declared an emergency and concentrated his mind and energy trying to land safely which he fortunately did.

So armed with this knowledge I am going to force the turbine to stay in the wind. Let's see where this all leads. I suppose I am about to learn why tails should not be fixed and why they should not be too BIG !!!

When I test something I like to change only one thing at a time because any more changes brings confusion. I know that place well. The big tail can wait, indefinitely if need be - the perspex and aluminium will not rust or decay and they can be applied to other jobs.

Anyway I tested the mast with the new 60 mm pipe supporting the turbine and leaving the existing tail on as it was and ........... I could have wept. It's improved quite a lot but is still not stable. The pipe deflects a couple of cms in a strongish wind.

I'm going to accept things as they are for the time being. I'll measure the inside parameters of my 10 cm boxed channel and eventually get the the biggest pipe that will fit that - I'm estimating at 80 mm OD. I'm going to the salvage and I'm going to ask them to hold any four or more metre long pipe of 80 mm OD (assuming that's the size) and then replace the two sections of 60 mm pipe. There will still be some deflection I suppose but of the order of millimetres and that will work. The stays will still attach just below the blades.

It's difficult to believe that the spinning blades and the turbine can bend that pipe over 1.7 m with the stainless steel pipes firmly mounted inside but it does and that's that.

With moderate winds everything's stable and I get 3 to 5 amps and I'll live with that for a while. For stronger winds I'll apply the electrical brake.